The authors investigate a rapidly rising glacial outburst flood (jökulhlaup) at the western Skaftá cauldron, Vatnajökull, Iceland, in September 2006. Outflow from the subglacial lake, flood discharge at the glacier terminus and the transient subglacial volume of floodwater during the jökulhlaup are derived from measured discharge and water temperature measurements in the pro-glacial river and the lowering of the ice over subglacial lake. Elmer/Ice is used to simulate an axi-symmetric approximation of the ice above the subglacial lake, which acts similar to an ice-shelf reacting on the elevation change of the water level. Consideration on the available thermal and potential energy along the 40 km initial subglacial water-path indicate that the jökulhlaup propagates by lifting and deformation of the overlying ice, induced by water pressure in excess of the ice overburden pressure and that melting of ice due to the heat of the floodwater from the subglacial lake and frictional heat generated by the dissipation of potential energy in the flow played a smaller role. Therefore this event and other rapidly rising jökulhlaups cannot be explained by the jökulhlaup theory of Nye (1976).
Read more: Einarsson, B., T. Jóhannesson, T. Thorsteinsson, E. Gaidos, and T. Zwinger, 2017. Subglacial flood path development during a rapidly rising jökulhlaup from the western Skaftá cauldron, Vatnajökull, Iceland, Journal of Glaciology, 1-13, doi:10.1017/jog.2017.33.